The Islamic State (IS) released a video on Thursday that purported to show a British hostage vowing to expose the “truth” about the group’s “systems and motivations” over the course of a “few programs”.

The clip features John Cantlie speaking from behind a table wearing an orange jumpsuit, mirroring the clothing worn by other hostages executed in IS videos.

Cantlie is a British war photographer who has worked with The Times and Sunday Times among others – he was captured in Syria by IS militants in July 2012.

IS has recently spread three videos on social media showing the executions of two American journalists and one British aid worker. However, the latest video does not show a beheading but instead shows Cantlie seemingly introducing what will become a series of clips.

The video cannot be taken as an expression of Cantlie’s views, given the likely duress he is under as a hostage, and he said as much when he spoke.

“Now, I know what you’re thinking,” he said. “You’re thinking: ‘he’s only doing this because he’s a prisoner he’s got a gun at his head and he’s being forced to do this,’ right? Well it’s true.”

“I am a prisoner that I cannot deny. But seeing as I’ve been abandoned by my government and my fate now lies in the hand of the Islamic State I have nothing to lose.”

Cantlie goes on to say that more videos will be released by IS “to show you [the viewer] the truth as the Western media tries to drag the public back to the abyss of another war with the Islamic State.”

He pledged to “show you [the viewer] the truth behind what happened when many European citizens were imprisoned and later released by the Islamic State, and how the British and American governments thought they could do it differently to every other European country.”

US and British governments have publicly said they will not negotiate ransoms with IS for the release of hostages. Other European nationals have been released by the group, after it appeared a ransom had been paid.

The BBC’s Security Correspondent Frank Gardener said previous IS videos have been directed at US and UK politicians but that Wednesday’s was clearly intended for public consumption and was particularly aimed at the Muslim community.

“It’s very much a propaganda video,” he said. “It doesn’t end with any overt threat even though it has clearly been made under duress and he’s reading from a script, there’s no knife or gun being held to his head.”

The video comes a week after IS released footage of Briton David Haines being executed, a clip which ended with the group threatening to behead Alan Henning, another British captive, if the UK continue to support airstrikes against them.

Alan Henning was taken by militants in December last year shortly after crossing into Syria from Turkey. He had been on an aid convoy to distribute assistance to Syrians suffering the consequences of their brutal civil war.

Earlier on Thursday a group of British Muslim leaders published a letter calling for Henning’s immediate release, arguing that anyone who takes part in humanitarian work should be respected and afforded protection.